This is a revision aid where students must read the 'notes' carefully and find the deliberate errors (and possibly undeliberate ones!). I have split (with some overlap) it up into three parts going from 'what is an expression/identity/equation?', through simplifying, expanding brackets, factorising into a bracket, solving equations, multiplying out 2 brackets, factorising quadratics and solving quadratics (factorising, completing the square and the formula). The aim is to get them active in their revision!